It has long been known that one or more cylinders of a multiple cylinder engine may be disabled from normal operation, i.e., cutout, to achieve a desired objective. For example, it is a widely followed practice to periodically cutout a cylinder for a brief period of time to monitor resultant engine operating conditions and thus determine if the cylinder and associated components are functioning within acceptable limits.
Cylinder cutout techniques may be employed for other purposes as well. For example, in U.S. Pat. No. 6,009,857, Hasler et al. disclose a system in which one or more cylinders are disabled to reduce the occurrence of white smoke. Engine speed and coolant temperature are monitored and when conditions exist which would cause white smoke, a fractional percentage of the cylinders are cutout.
There are engine operating conditions which may exist in which an engine may run unstable, i.e., the speed of the engine may fluctuate more than allowable from a desired speed. For example, an engine running at an idle speed, e.g., a marine engine at idle, may tend to fluctuate from the desired idle speed due to nonlinearities associated with operating parameters such as fuel delivery. These fluctuations in speed are often undesirable and it would be preferable to cause the engine to operate under more linear portions of operating curves to reduce the fluctuations.
The present invention is directed to overcoming one or more of the problems as set forth above.